VFD driver L2906-02

Discussion in 'General Electronics Chat' started by matelot, Mar 19, 2017.

  1. matelot

    Thread Starter Member

    Apr 15, 2013
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    I would like to try to reverse engineer a VFD from a DVD player.
    The board has a large chip on the back that has tracks to all of the pins of the VFD. I assume this is the driver.
    I would like to find more info about this chip.
    It has, I am fairly sure, L9206-02 or L9208-02 on it and 4282204J.
    I assume the 4282204J is a serial number but a google search brings nothing up about a driver chip with a number similar to the first two.
    Can anyone shed any light on where any info could be found for this chip?
    Thanks.
     
    Last edited: Mar 19, 2017
  2. DickCappels

    Moderator

    Aug 21, 2008
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    What brand was the player? Any indication of the chip's manufacturer such as a logo (clear photo if you don't recovnize it)?
     
  3. matelot

    Thread Starter Member

    Apr 15, 2013
    34
    3
    Thanks Dick,
    I don't know which set it came from.
    It looks as if someone on the manufacturing side has swiped across the face of it with a black felt tip and then a brown felt tip.
    I have been reluctant to try to remove this, worrying that I might lose the indication altogether.
    This evening I gave it a good wipe with white spirit and managed to get OKI japan from below the felt tip as the first line and a clearer view of the numbers, albeit only if I get it in a good light under a lens light. It is L9208-2.
    I will investigate further and see if I can get anything now I know it is OKI.
     
  4. matelot

    Thread Starter Member

    Apr 15, 2013
    34
    3
    I just tried another google search on OKi l9208 and got a hit. I now have a data sheet for the driver.
     
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  5. matelot

    Thread Starter Member

    Apr 15, 2013
    34
    3
    The data sheet is here
    http://www.alldatasheet.com/datasheet-pdf/pdf/577694/ETC2/ML9208-02.html
    For the driver.
    I have tried to trace the wires back to the plug on the board but am getting multi connections.
    I suspect some of it might be to do with the fact that there may be a need off board to control the running of the display.
    I.E. two pins need to be connected to make it work etc.
    I put 5v on what I thought was the input pins and got 5v across the driver chip power pins. I also got 5v on both the grid pins of the display with respect to the neutral pin of my power supply, I think I should get about 3.3v across the two grid pins.
    I tried to poke a signal into the data pin, setting the clock and latch pins as I went but nothing showed up on the display.
    I have tried a few other things but suspect, as I wrote earlier there is a need to connect other pins in other ways to make it work.
    I am now trying to find any more info about the board.
    The board is pictured below
    [​IMG]
    [​IMG]
    I have googled all the numbers on it without success. I don't even know which unit it came from.
    I googled the chip without success until I added 'OKI' into the search so if I keep trying different things I might get somewhere.
    What company is the UR backwards?
    Can anyone shed any light onto what this board might be and what pins on the 9 pin socket in the bottom left corner of the top picture and bottom right corner of the bottom picture might go where?
    Is there a standard for this socket used in this way?
    Any advice would be welcome.
     
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  6. DickCappels

    Moderator

    Aug 21, 2008
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    You wrote:
    What company is the UR backwards?

    It is a safety mark that indicates that the assembly meets Underwriters Laboratories's criteria which mostly relate to fire and electrical shock hazards.

    I don't see anything that looks like a 15 volt or higher power supply -what are your input voltages? I think the lowest anode voltage VFD needs at least 10 volts. See anything like that.

    Now that you have the datasheet for the controller chip, if you can find the datasheet for the VFD and you can buzz out the circuit accurately you just, just might, mind you, be able to figure out what else you need to get it working.
     
  7. matelot

    Thread Starter Member

    Apr 15, 2013
    34
    3
    I think the power supply required is 5v.
    If you look at the circular soldered ring to the left of the top picture it is surrounded by a number of inductors and capacitors, I think this is the generator for the 3.3v the grid needs and the ring looks not unlike a small toroidial transformer that possibly supplies the higher voltage of the anode. I am assuming everything the system needs in the way of power is on the board.
    There is a long connector under the audio sockets but I reckon that is just to connect to those sockets.
    I have a similar display working with an arduino using 74hc595s to supply all the pins and uln2803s to supply the power.[​IMG]
    As you can possibly see from the photo it is getting rather crowded and I only light three symbols at the present.
    I picked up the top board from a box of boards I had dismantled earlier hoping to get it to work just using the serial input and not needing all the wires of the bottom picture.
    Do you recognise the other symbols on the board?
    They look like a stylised LF or FF? (the bottom of the lower of the two board pictures).
     
    Last edited: Mar 23, 2017
  8. DickCappels

    Moderator

    Aug 21, 2008
    4,050
    1,164
    The stylised LF and the FF do not ring any bells.

    If you know the manufacturers and models of the DVD players you scrapped you might get lucky and find some documentation for them and then figure out which one includes your display from that.
     
  9. matelot

    Thread Starter Member

    Apr 15, 2013
    34
    3
    I have tried finding the rest of the unit but without luck.
    I have seen the <PF-LP> symbol on other boards but I can find nothing about them either. All google searches show up palestine liberation army, I am sure it's not them who printed the boards.
    I think the 3,5v grid and the 15v power are produced on the board so all I would need is to know the pins on the board input plug to run it from 5v
     
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